Method of manufacturing molds



Patented July 24, 1934 UNITED STATES PATENT OFFICE METHOD OFMANUFACTURING MOLDS No Drawing. Application January 31, 1931, Serial No.512,739. In Germany April 3, 1930 1 Claim.

My invention relates to improvements in the method of manufacturingobjects from porcelain or cast metal and in the mold used in the saidmethod, and more particularly in the method used for example in themanufacture of fillings for teeth in which the plug is made by means ofa mold shaped according to the cavity of the tooth. In the manufactureof such plugs it is necessary to coat the mold with a thin metal foilordinarily made from a noble metal such as platinum or gold, in order toprevent baking together of the plug and the mold when burning or castingthe material. The object of the improvements is to provide a method bymeans of which the said coating may be applied in a most simple way,

and in which the said coating is exceedingly thin and dense, and withthis object in view my invention consists in applying the coating incolloidal form and together with a carrier thereof.

For the purpose of explaining the invention more in detail severalexamples embodying the same will now be described.

In accordance with my invention I add the metal in colloidal solutionsto the material from which the mold is manufactured, I manufacture themold from the said material, and I heat the mold either before or afterputting the porcelain or metal from which the plug is made into thesame. By thus heating the mold a very thin and dense metal coating isproduced. The method 3 is important not only in the manufacture ofobjects from porcelain by molding, but also in the manufacture ofcomplicated objects of metal such as tooth plugs made from metal. In themanufacture of such plugs the metal may be immediately cast into themold in which the cavity is not provided with a metal coating becausethe cast metal does not adhere to the mold. However if a coating is notused it happens that 50 minute air bubbles are left between the Walls ofthe mold and the material cast into the same which produceirregularities on the surface of the metal casting. When coating themold in the manner described above by means of a colloidal 55 metalsolution this objection is obviated, and it is possible to manufactureexact tooth plugs or other pieces of metal of very complicated shape bycasting the metal into a mold which before has been coated by colloidalmetal. 7

While in describing the invention reference has been made to particularexamples embodying the same I wish it to be understood that my inventionis not limited to the methods of applying the coating of colloidal metaldescribed herein, and that various changes may be made in the saidmethod without departing from the invention.

I claim:

The herein described method of manufacturing molds for making porcelainfillings for teeth, consisting in applying a colloidal metal solution byadding the same to the basic mass from which the mold is made, making animprint, and heating the mold after the imprint, thereby causingevaporation of the solution agent of said colloidal metal solution, sothat a colloidal metal coating forms on the surface of the mold.

EUGEN BRILL.

